Former San Diego mayor Maureen O’Connor’s attorneys argued this week that a tumor contributed to her betting more than $1 billion and losing $3 billion over a decade.

Appearing in federal court, O’Connor also admitted to stealing $2.1 million from the charity foundation set up by her late husband, Jack in the Box founder Robert Peterson, to fund her video poker habit. The Justice Department agreed to defer prosecution as she attempts to repay the debt. Since 2001, IRS records suggest that her winnings totaled $1 billion— but her losses were even greater. If O’Connor gets treatment and makes restitution, the charges may ultimately be dropped.

O’Connor was San Diego’s first female mayor, serving from 1986 to 1992. Before that she had been a physical education teacher in a Catholic school; during her first campaign, according to the New York Times, she was described as a “goody two shoes.” She grew up poor, as one of 13 children, but married the founder of the Jack in the Box restaurant chain, inheriting $40 to 50 million when he died in 1994.

It was her husband’s death, her lawyer Eugene Iredale wrote in legal papers, that triggered O’Connor’s problem of “grief gambling,” which only worsened with the loss of other loved ones. She started gambling in 2001, playing hour after hour of video poker in casinos in San Diego, Las Vegas and Atlantic City. She eventually became such a high roller that casinos would fly her in for free on a private jet. In her best year, she reported winnings of some $200 million to the IRS.

O’Connor was diagnosed with a brain tumor, which was removed in 2011. And as her gambling losses increased, her lawyers say, she began stealing from her husband’s charitable foundation and selling properties to support the addiction that ultimately took away nearly her entire fortune. She now lives with her sister.

Did her tumor contribute to the gambling problem, as her attorneys maintain? Prosecutors argued that the ex-mayor’s compulsive gambling began long before the tumor could have affected her— and it’s not clear whether the surgery resulted in a complete end to the gaming, given that the terms of the deferral require ongoing treatment. Experts say, however, that depending on the location in the brain, it’s certainly possible for a tumor to profoundly affect behavior. Tumors can influence the release of brain chemicals such as dopamine and serotonin that regulate feelings of reward and satisfaction and are crucial for motivation, as well as other agents involved in generating these feelings. Altering the delicate balance of these compounds can lead to either a constant hunger for a reward that never seems to materialize, or a single-minded craving to pursue behaviors such as gambling.

“I think it’s like real estate: location, location, location,” says Dr. Howard Shaffer, associate professor of psychiatry at Harvard Medical School and author of Change Your Gambling, Change Your Life. “If [a tumor] is in a frontal area it might disturb organization or braking mechanisms. If it’s in another region, like closer to the ventral tegmental area, it might have more to do with energizing impulses.”

Some of the clearest and most disturbing examples of tumors changing behavior come from cases of pedophilia that have been reported to occur spontaneously in men with no prior history of such behavior. In a case reported in 2003, a 40-year-old school teacher suddenly began collecting child pornography. He tried to molest his stepdaughter and sexually propositioned nearly every female he saw. He was arrested and promptly failed an attempt at treatment.

But the day before he was due to start his sentence, he developed a headache so painful that he went to the emergency room, leering at the nurses even as he sought help. A brain scan showed a tumor the size of an egg, squeezing his right frontal lobe, an area involved in judgment and self control. When the tumor was removed, his lewd behavior ceased— but a recurrence several years later brought it back until the growth was removed again.

Charles Whitman, however, represents perhaps the most famous case in which a brain tumor was associated with deviant behavior. Whitman committed one of America’s first mass school shootings in 1966, gunning down 14 and wounding 32 from a tower perch at the University of Austin in Texas. Whitman had complained of increasingly intense headaches and strange urges preceding the murders, as he wrote in his diary and notes. And an autopsy revealed a large tumor affecting his amygdala, an area involved in regulating anger and fear.

Tumors, of course, are not the only brain factors that can influence behavior. Compulsive gambling and sexual behavior can also emerge when people take drugs for medical reasons, if these medications end up affecting brain regions involved in addictions. Drugs used to treat Parkinson’s disease, for example, tend to raise levels of dopamine, a neurotransmitter involved in pleasure and motivation.

“When you take [these] drugs, you inherently increase the availability of dopamine,” says Shaffer. “People say that this causes pathological gambling. No. It causes all kinds of things depending on the opportunities available and the social setting. A brain tumor can cause disinhibition, and disinhibition will get expressed differently depending on the environment.”

A French man successfully sued GlaxoSmithKline for nearly $300,000 after he became a compulsive gambler and began engaging in risky gay sex, while taking the company’s drug Requip for Parkinson’s Disease. Requip mimics the action of dopamine and the married father of two had not previously engaged in gay sex. When he stopped taking the drug, his compulsive need for sex stopped. The medication now includes a warning about potential loss of impulse control that could lead to multiple types of addictions.

While it’s clear that tumors can therefore influence behaviors like gambling and other addictions, what is less obvious is how this understanding translates into legal responsibility. Was O’Connor’s compulsive gambling caused by a simple gambling addiction, which itself can diminish control over behavior? Or did the tumor make her loss of control over her actions even more severe? And if so, how responsible is she for her failure to rein in her betting?

“The tumor would not render her less responsible per se,” says Stephen Morse, Professor of Psychology and Law in Psychiatry at the University of Pennsylvania, “If it could be shown that it in part produced a genuine excusing or mitigating condition, such as diminished rational or control capacity, then it would strengthen the case for lesser responsibility because the cause of the excusing or mitigating condition was not her fault, at least in part.”

Morse doesn’t see brain tumors as being different from other kinds of mitigating factors, whether social or biological. “We tend to assume that the person could not have controlled herself if an abnormal biological cause such as a tumor is present. But even then, we can rarely confidently assert that the person could not control herself rather than simply did not.”

Dr. Mark Willenbring, former director of treatment and recovery research for the National Institute on Alcohol Abuse and Alcoholism, says that confidence may grow if future research identifies biological processes that are responsible for triggering certain behaviors such as addictions or sexual deviance. “Whether to hold someone responsible for their actions would depend on how the tumor or other disease process affected them. If the result was an inability to understand the difference between right and wrong, or delusional beliefs such as thinking that someone is trying to kill me, that drove the behavior, then I would say they should not be held responsible.”

But that may still not be enough to excuse criminal behavior. “Psychopaths lack empathy for other people because of genetic and genomic processes. But we don’t excuse serial murderers because they lack empathy,” he says. Biology and genes may explain much about human behavior, but that understanding still has much to prove in a court of law.

2 BIL buys a very good psychiatrist, good neurologist, and LOTS of therapy. Our severely mentally ill children go to jail in the US every single day. Cook County Jail is now known a psych hospital. But she's a 'city treasure,' who's funny and sweet. How sickening! This city treasure stole 2 mil from a charity! She has more than reasonable capacity, and our severely mentally ill children are jailed for break ins, scaring people, and violence because there are NO proper treatments funded, no psych beds, no outpatient comprehensive services, severe limits on insurance policies, and they aren't RICH. She bankrupted herself by gambling; we bankrupt ourselves trying to keep our children in hospitals and self-paying psychiatric costs that are sky-high and uninsured. and obtaining good meds, which can costs thousands every month. If you don't believe me, run out and get yourself some schizophrenia, which is not a choice and is progressive, chronic, debilitating brain disease, just like a tumor. This is one of the most disgusting, inequitable displays of over-privileged excuse I've ever read. If our children have to go to jail for small infractions while completely incapacitated, SHE can go to jail for a decade of theft and get the same treatment they do: NONE. And it's lovely to think her 2BIL could have purchased so much help for the homeless on the streets of HER city, many, many, many of whom are severely mentally ill, but it went to video poker? Justice for the Rich only: this ridiculous woman should be treated like my son and the children of a hundred parents I know of very sick children whom you can't services for, who are judged competent if they're over 18 years old, and whom she stepped over for years on the way to city hall in San Diego: JAIL. AND MORE JAIL.

@bibleverse1 Spoken like someone who has no clue what a brain tumor can do to a person. I have no idea if this lady stole because of her tumor or not, but as the husband of a brain tumor survivor, I can tell you that brain tumors have a LOT of first, second, and third order effects. Doing the right thing isn't always a matter of will power. Good people can do bad things because they can't help it. That doesn't make it any easier to be one the receiving end, but it can help the receiver keep things in perspective.

And..while..there may be many reasons for inappropriate and illegal behavior, physical and otherwise, a person should STILL have to take responsibility and accept the legal consequences for it. It may seem "unfair', but ... we all have to accept consequences of behavior (despite what initiated it).

@foponlyYes, and no. It's not nearly as simple as you make it out to
be. People should be held accountable for the actions they have control over.
But brain tumors are tricky beasts. If a person kills someone else in a car
accident because they had a seizure while driving, should they be held
accountable? If it's the first incident from an undiagnosed disorder, then I
say no. If they know they shouldn't be driving, then yes.

Behavior is an even trickier ethical issue. Have you ever
said anything you didn't mean when fighting with your spouse? Most of us would
agree that when fighting, there is a certain compulsion to say mean things. We
are still held accountable when we do, but what happens when a brain tumor
removes the filter that prevents us from saying the worst things that pop into
our heads? What if you can't help but say what you think? Should I divorce my
wife because her filter was lost as a result of her brain surgery? Should I
hold her accountable? What kind of person would that make me? Is there a
learnable lesson I can teach her?

@actions.junkmail Not necessarily. I have a cysts on the pineal gland of my brain. Technically it's a brain tumor, but it's benign so not, at the moment, life threatening. It could grow and/or burst, and kill me, but that's not definite.

lets just blame every stupid action or irresponsible behavior on mental or social environment and let every one out of prison. every action causes a reaction that does not mean its a justified excuse to do something stupid.